While some indicators show the climate phenomenon has been developing in recent months, others favor more neutral conditions, or at least a weaker El Nino than was previously expected.NOAA's Climate Prediction Center detailed the forecast in a monthly update that extends an El Nino watch that has been in effect since June.

The World Meteorological Organization last week also downgraded its expectations of El Nino, calling for a weak version to set in by the end of this month. Earlier this year, forecasters had expected El Nino to set in by August or September.

The world has been on watch since June for an El Nino climate pattern to develop by the fall. While it hasn't yet, it could arrive next month, albeit a weak version of it, according to the World Meteorological Organization.

Pluto's "heart" contains shifting glaciers of frozen nitrogen, methane and carbon monoxide, and its atmosphere is both deeper and disappearing more rapidly than scientists predicted, New Horizons mission leaders said Friday.